Katy Perry and John Mayer ring in 2016 together

Katy Perry and John Mayer have sparked rumors their romance is very much back on after leaving a Hollywood hotspot together early on Thursday morning (31Dec15).

The on/off couple was spotted partying together at The Nice Guy and one insider insists the singers looked like they were an item.

Perry, who has been dating Mayer on and off since 2012, also performed at the club, reportedly singing a moody version of Carole King's (You Make Me Feel Like a) Natural Woman.

The private pair have always refused to address rumors about the romance, but Mayer and Perry also appeared to be together at mutual friend Allison Williams' wedding in September (15), when they held hands and sat next to each other.

They were also spotted together at the Grateful Dead's farewell concert series in Chicago, Illinois over the summer (15).

The Nice Guy has become a top hook-up spot for stars - Zayn Malik and Gigi Hadid spent three nights there in the same week after meeting at Justin Bieber's American Music Awards after party in November (15).